Self-threading sewing machine needle

ABSTRACT

A sewing machine needle in which a threading slot extends lengthwise along the needle blade and opens into the needle eye. The slot is spaced transversely further from the needle center line than the adjacent wall portion of the eye below the terminus of the slot. The wall portion of the eye above the slot terminus merges with the inner wall of the slot at a location transversely further from the needle center line then is the eye wall portion below the terminus so that a transverse offset is provided.

United States Patent 11 1 Zocher 1451 Jan. 7, 1975 1 1 SELF-THREADING SEWING MACHINE NEEDLE [75] Inventor: Josef Zocher, Haaren/Aachen,

Germany [73] Assignee: The Singer Company, New York,

[22] Filed: June 25, 1973 [21] Appl. No.1 372,459

[52] U.S. Cl. 112/224 [51] Int. Cl D05b 85/02 [581 Field of Search 112/222, 223, 224, 225; 223/102 156] References Cited UNITED STATES PATENTS 752,213 2/1904 Farmer 112/224 1,441,575 l/l923 Granger 112/224 Trejo Rattie FOREIGN PATENTS OR APPLICATIONS 258,774 4/1913 Germany ..'.ll2/224 70,818 12/1915 Austria ..ll2/224 Primary Examiner-Werner H. Schroeder Attorney, Agent, or Firm-Robert E. Smith; Edward E. Bell; Alan Ruderman [57] ABSTRACT A sewing machine needle in which a threading slot extends lengthwise along the needle blade and opens into the needle eye. The slot is spaced transversely further from the needle center line than the adjacent wall portion of the eye below the terminus of the slot. The wall portion of the eye above the slot terminus merges with the inner wall of the slot at a location transversely further from the needle center line then is the eye wall portion below the terminus so that a transverse offset is provided.

3 Claims, 3 Drawing Figures SELF-THREADING SEWING MACHINE NEEDLE BACKGROUND OF THE INVENTION This invention relates to sewing machine needles and more particularly to a needle of the self-threading type. The known self-threading sewing machine needles which include a slot for facilitating threading of the needle, which slot extends into the needle eye, have not proven satisfactory because of their tendency to pick and chafe the thread as the needle reciprocates during high speed sewing. This has always been a problem in the prior art but is magnified by the higher speeds at which modern sewing machines operate.

Typical of the prior art needles are U.S. Pat. Nos. 2,221,419,1,924,378,1,235,751 and 623,666 in which the threading slot enters the eye through one of the eye defining walls that engage and guide the thread. Since during machine sewing each increment of thread translates many times back and forth at high speed through the eye before it is utilized in a stitch, the continuous rubbing of the thread against the opening in the eye wall causes a chafing and weakening of the thread. Moreover, since a sewing thread comprises a plurality of strands, as the thread passes the threading slot opening in the wall, the edge of the opening picks at the strands. Other approaches taken by the prior art as exemplified by U.S. Pat. No. 653,886 include the formation of a tongue to separate the eye proper from the slot, but this is an extremely expensive needle making it financially impracticable for use. U.S. Pat. No. 738,567 discloses yet another approach which generally increases the thread chafing and tearing.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide a self-threading needle in which the thread is protected against chafing and picking.

It is another object of this invention to provide a selfthreading needle in which the thread in the eye is prevented from enagaing the threading slot.

It is a further object of this invention to provide a self-threading needle in which the upper wall of the eye above the threading slot terminus is transversely offset from the lower wall of the eye below the terminus.

These objects are obtained by providing a selfthreading needle in which a lengthwise threading slot terminates between the upper and lower extremities of the eye, the lower wall of the eye below the slot terminus is transversely intermediate the needle center line and the threading slot, and the upper wall of the eye above the slot terminus into the slot transversely between the slot and the lower wall of the eye. Moreover, the upper wall arcuately curves upwardly away from the lower wall. These provisions insure a needle in which the thread as it translates through the eye moves from the lower eye wall to the upper eye wall without engaging the thread slot, and is moreover, forced by the upper wall contour away from the slot.

BRIEF DESCRIPTION OF THE DRAWINGS The particular features and advantages of the invention, as well as other objects, will become apparent from the following description taken in connection with the accompanying drawings in which:

FIG. 1 represents an elevational view of a selfthreading sewing machine needle embodying the present invention as viewed from a position looking through the needle eye and with the width of the threading slot exaggerated for clarity;

FIG. 2 is a greatly enlarged elevational view of a fragment of a semi-finished needle in accordance with the present invention viewed in a direction looking through the needle eye; and

FIG. 3 is a greatly enlarged elevational view of the same fragment of .the needle as shown in FIG. 3 but showing the needle in finished form.

DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated in the drawings, the needle of this invention is formed with a shank 12 which may be slabbed in the rear surface (not shown) of FIG. 1 for orientation in a sewing machine needle clamp. From the shank, the needle tapers to a blade portion 16 which, at the opposite end of the shank, is formed with a pointed extremity l8. Adjacent to the pointed extremity the needle blade is formed with a transverse thread carrying eye 20 through which a sewing machine thread must extend during sewing operation. With the exception of the eye portion of the needle, the needle of the present invention is the same as that disclosed in my U.S. Pat. No. 3,645,222, and includes a long thread accommodating groove 22 and a shorter groove not shown for purposes explained in my said U.S. Pat.

In order to facilitate insertion of thread into the needle eye 20 the needle blade 16 is split into two lateral segments 24 and 26 by a threading slot 28 which extends from the juncture of the needle blade 16 with the shank 12 to the needle eye 20. As illustrated in FIGS. 1, 2 and 3, the threading slot 28 is formed along one edge of and opens onto the thread accommodating groove 22. Adjacent to the juncture of the needle shank 12 with the needle blade 16, a transverse thread inlet slot 30 is formed across the needle so as to open onto the threading slot 28 to provide a path for thread insertion into the threading slot 28 As illustrated in FIG. 1 the needle of the present invention is twisted about its longitudinal axis greater than for reasons which are explained in my aforesaid U.S. Pat. to which further reference is made for a fuller understanding of the needle above the eye portion.

The eye 20 comprises an aperture formed between walls 32 and 34 of the blade adjacent the pointed extremity 18. The eye preferably is elongated longitudinally along the center line CL. of the needle with the lower or point directed longitudinal extremity of the eye having'a substantially semicircular shape 36. The threading slot 28 which is transversely spaced from the needle center line C.L. terminates intermediate the lower extremity 36 of the eye wall 32 and its upper extremity 38 and communicates with the eye. Preferably, as illustrated, the terminus of the threading slot is longitudinally spaced nearer the top 38 than the bottom 36. The eye wall 32 adjacent the threading slot 28 is transversely intermediate the slot 28 and the center line CL. and includes a slight shoulder 40 which merges into the segment 24 forming the transversely outer wall 42 of the slot 28.

The eye wall above the terminus of slot 28 extends transversely further outwardly then the wall below the slot terminus and merges into the wall 44 of the segment 26 which wall forms the transversely inner wall of the slot. This location of mergence 46 overlays the thread which will tend to ride up the wall 32 will be deterred from entering the slot 28 or engaging the edge 46 since it will jump from the wall 32 to the surface .38.

To aidin directing the thread T away from the wall 32 and towards wall 34, the upper wall 38 is not semicircular as 36 but is somewhat elipitical. At any rate the contour is arcuately curved upwardly and preferably has its crest 48 on the opposite side of the needle center line from the thread slot. The shape of the arcuate surface from 46 to 48 is such as to force the thread away from wall 32 and towards wall 34 when the thread T is in contact with that surface. Thus, on the needle upstroke the thread will tend to ride down wall 34 and not engage the shoulder 40.

The needle of the present invention may have the eye formed by known die pressing operations while the thread slot may be cut as described in my aforesaid US. Pat. No. If the slot 28 is cut as described in said patent it will have a considerable width, as shown in FIG. 2, and must then subsequently be pressed to substantially completely close the slot, as shown in FIG. 3.

Thus, a self-threading needle has been disclosed which substantially eliminates chafing and picking of the thread and which is relatively inexpensive to manufacture as compared to the prior art. Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of the invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having thus set forth the nature of the invention, what is claimed herein is:

1. A self-threading elongated sewing machine needle including a shank adapted to be clamped to the sewing machine, a blade extending from the shank and terminating in a pointed extremity formed with a longitudinally elongated thread carrying eye, said eye comprising an aperture defined between spaced wall portions of said blade, said blade being formed with a lengthwise thread accommodating groove extending from said thread carrying eye towards said shank, a lengthwise threading slot formed through said needle blade transversely spaced from the needle center line and terminating intermediate the upper and lower extremities of one wall portion of said eye, said threading slot opening into said thread accommodating groove at one side of said needle, a thread inlet groove formed transversely in the needle blade and opening into the threading slot,

said one wall portion below the terminus of said slot being intermediate said slot and said needle center line and having a transverse shoulder merging with the transversely outer wall of said slot, said one wall portion above the terminus of said slot being arcuate and merging with the transversely inner wall of the slot at a location overlaying said shoulder and transversely intermediate said wall portion below the terminus of said outer 'wall of the slot.

2. A self-threading needle as recited in claim 1 wherein said wall portion above the terminus of said slot is arcuately curved upwardly from. the location of mergence with the outer wall of said slot-toward the other wall portion of the eye.

3. A self-threading needle as recited in claim 2 wherein said shoulder is on a first side of said needle center line and said arcuately curved 'wall portion crests on the opposite side of the needle center line. 

1. A self-threading elongated sewing machine needle including a shank adapted to be clamped to the sewing machine, a blade extending from the shank and terminating in a pointed extremity formed with a longitudinally elongated thread carrying eye, said eye comprising an aperture defined between spaced wall portions of said blade, said blade being formed with a lengthwise thread accommodating groove extending from said thread carrying eye towards said shank, a lengthwise threading slot formed through said needle blade transversely spaced from the needle center line and terminating intermediate the upper and lower extremities of one wall portion of said eye, said threading slot opening into said thread accommodating groove at one side of said needle, a thread inlet groove formed transversely in the needle blade and opening into the threading slot, said one wall portion below the terminus of said slot being intermediate said slot and said needle center line and having a transverse shoulder merging with the transversely outer wall of said slot, said one wall portion above the terminus of said slot being arcuate and merging with the transversely inner wall of the slot at a location overlaying said shoulder and transversely intermediate said wall portion below the terminus of said outer wall of the slot.
 2. A self-threading needle as recited in claim 1 wherein said wall portion above the terminus of said slot is arcuately curved upwardly from the location of mergence with the outer wall of said slot toward the other wall portion of the eye.
 3. A self-threading needle as recited in claim 2 wherein said shoulder is on a first side of said needle center line and said arcuately curved wall portion crests on the opposite side of the needle center line. 